1) Field of the Invention
The present invention relates to a device for containing material released by or into a rotary device such as a turbine.
2) Description of Related Art
Many rotary devices include a surrounding structure for containing fragments that are released by the device during a failure. For example, a conventional rotary device such as a flywheel has a housing that surrounds the flywheel. The housing can be a strong, rigid structure designed to withstand the impact of pieces, or fragments, of the flywheel that are released if the flywheel breaks while operating at a high rotational speed. Due to the high speed and/or mass of conventional rotary devices, the fragments released during failure can have significant kinetic energy. Therefore, the housing must be strong in order to contain the fragments, typically requiring a thick housing that adds weight and cost to the device.
U.S. Pat. No. 6,182,531, titled “Containment Ring for Flywheel Failure,” which issued Feb. 6, 2001, describes a containment vessel that includes an outer ring with a plurality of inner shaped elements that produce an inner ring layer. The inner shaped elements are juxtapositioned axially along the inner periphery of the outer ring and configured to produce hollow cells that plastically deform to absorb the energy from an impact of a high energy material fragment, such as are produced during catastrophic failure of a flywheel. The inner shaped elements are configured to deform at a sufficiently fast rate to prevent the inner shaped elements from rupturing or buckling.
An increased likelihood of piercing or otherwise damaging a housing or containment vessel exists where the rotary device has sharp edges extending radially outward. However, even where the rotary device does not have sharp outer edges, sharp edges can be formed if the rotary device fails. For example, typical flywheels that are used for energy storage often fail by breaking into three segments. Each segment, which can have sharp edges at the point of breaking, typically rotates as the segment moves radially outward. The rotation and path of travel of each segment are determined in part by the speed of the flywheel, the material of the flywheel, the size of the segment, and the location of the center of mass of the segment. The housing or other containment vessel for a flywheel is typically located near the flywheel, as illustrated in the figures of U.S. Pat. No. 6,182,531. Thus, only limited rotation of the segments can occur before the segments collide with the housing, thereby limiting the possibility that the broken edges of the segments will contact the housing. On the other hand, if the housing or other containment vessel is located some significant distance from the flywheel or other high energy rotary device, piercing and other damage is more likely to occur.
Thus, there exists a need for an improved containment device that can contain materials released by or into a rotary device, and a rotary turbine with such a containment device. The containment device should be able to contain materials with significant kinetic energy. Further, the containment device preferably should reduce the likelihood of piercing or other damage that results from materials that define sharp edges or points.